Loading-coil and method of constructing same



w. 1. SHACKELIUN. LOADING COIL AND METHOD OF CONSTRUCTING SAME.

APPLICATION FILED AUG-$1918. v I Pgtented Mar. 23, 1920.

2 SHEETS-SHEET I.

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/7// III -W. J. SHACKELTON.

LOADING COIL AND METHOD OF CONSTRUCTING SAME.

APPLICATION fILED AUG-9, 1918.

1,334,321. Patented Mar. 23, 1920.

2 SHEETS-SHEET 2.

7 g 2/22 25 w w 24 2526 27/27 /27 v2g 2950 3/ ed /.3/ a; 1111 51/32/75- v UNITED STATES PATENT OFFICE.

WILLIAM J. SHACKELTCN, OF SCOTCH PLAINS, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC CCMPANY,INCORPORATED, OF NEW YORK, N; Y., A CORPORATION OF NEW roan.

LOADING-COIL AND METHOD or consmucrme SAME.

Specification otLetterS Patent.

Patented 31211223, 1920.

Application filed August 9, 1918. Serial No. 249,068.

To all whom 2'1 may concern:

Be it known that I, WILLIAM J. Snaoxnn- TON, a citizen of the United States, residing at Scotch Plains, in the county of Union,'.

' to means 'for reducing or preventing inductive interference or. eross-talkbetween'the circuits of systems in which'the same loadin}; unit is used to load more than one circuit, as may be done in the case of two physlcal circuits and their derived phantom circuit.

In order that the cross-talk arising in such a loading unit shall be a minimum, the mutual inductances .between each of the line windings in'one physical-circuit and those in the other physical circuit should be equal.

01' at least very nearly so. For, if one line wipding ismore susceptible than the other liiie windin of the same physical circuit to the VEHlittlOIlS of flux accompanying s eech currents flowing in the windings of the other physical circuit cross-talk currents will be set up in the first circuit due to the inequality of electromotive forces induced in its two. windings and their consequent failure to balance each other; in like manner inequalities of mutual inductance between the ,windings may cause cross-talk between either of the physical circuits and the derived phantom circuit.

Inequalities of mutual inductance may arise, for instance, from lack of homogene' ity as to permeability of the core of the loading unit, such as may be caused in cores made up of laminations or the like by differences in the .laminations or the closeness of their contact.

"which amp] I The efiects of .sughinequalities, thou h perha s negligible in short lines in whic low vo tages'nnd small currents are encoi lntered, become accentuated toa harmful degree under the. high; pressures occur-" aloading unit in which the'mutual induc-- tances between the several windings are so closely balanced as to prevent appreciable cross-talk under severe service conditions;

a further object is to afford a method for producing such a condition of balance.

Further obJects and advantages of this invention Will beapparent from the following detailed description read in connectlon w th the accompanying drawings, in

which Figure 1 represents the application of a loading unit employing thisinvention to the simultaneous loading of two physical circuits and their derived phantom circuit; Fig. 2 illustrates diagrammatically the windings employed; Fig. 3 illustrates more in detail the type of core used in the loading unit shown in Fig. 1; Fig. 4 shows. the invention incorporated in a different form of loading unit; and Fig.- 5 illustrates diagrammatically the windings employed in Fig. 4.

Referring to Fig. 1,.I indicates one physi'-.

cal circuit "comprising the line vconductors 101 and 102, II indicates the otherphysical circuit comprising the line conductors 103 and 104 and III indicates a phantom cir-. cuit derived from such physical circuits in a well-known manner. The loading unit illustrated in this figure has four semiannular core sections 1, 2, 3 and 4, joined together in such manner as to form in eflect two complete rings intersecting 'at right angles on. a common diameter. rings may be of any suitable magnetic ma terial but are preferably formed of finely divided iron.with the individual particles insulated from one another, this material being molded under high pressure into the required form. As shown in Fig. 3 the members of the core may be built up of a plurality of layers or laminations 5, which may be secured together in any appro riate manner. A core of this type is descri in detail Speed Patent 1,221,238, dated April 3,191

The core sections 1, 2-, 3 and 4 are provided with the main windin 10-41, 12- -13,

1415 and 16+17, respectively. Upon each core section there is also mounted a sup le-' mentary or auxiliary winding prefera bly surrounding a. portion of the main winding. The supplementing section is connec in series with the main winding on an adj scent coresection thus the supplementary .winding 116-111 on core section 2 is m series with main '10- 11 on core section 1; similarly supplementary' 112-118 on core sodium The two winding on eachcore 114-115 on core'section 3 is in series with main winding 14-15 on core section 2, and supplementary winding 116-117 on core section 1 is in series with main winding 16-17 on core section 4. In this arrangement, when the loading unit is connected to the line conductors as indicated in Fig. 1, the main windings on one pair of opposite core sections, as 1 and 3, or 2 and 4, and the supplementary windings on the other pair of opposite core sections, 2'. 0., 2 and'4, or 1 and 3, are-in series in one of the physical circuits, as I or II respectively; that is,

the core sections having main windings for either physical circuit alternate with core sections carrying the supplementary windings belonging to that physical circuit.

After the core sections 1, 2, 3 and 4 have been assembled, with the main windings arranged thereon so as to approach, as nearly asis practicable by means of a preliminary design, to an equality of mutual inductance between the respective windings, the supplementary windings are placed on the core, their position and number of turns being determined in the followingmanner:

A closed circuit is formed which comprises a telephone receiver and the windings on-two opposite core sections, for instance windings 14-15 on core section 2 and windings 16 17 oncore section 4, the core windings being connected in this circuit in the same relation as would be the case in physical circuit II as shown in Fig. 1 of the drawings." A current of telephonic frequency is applied to one of the other main windings, as winding 10-11 on core section 1; this current produces a varying magnetic flux in core section 1, which flux divides at the junction ploints of the core'sections and passes throng the core sections 2,. 3 and 4,

Since the two portions of the flux in sections 2. and 4 pass in opposite directions through the material of the ring formed by these sections while the turns of windings 14-15 and 16-17 follow the same direction around the ring, it is apparent that the electromotive force induced in winding 14-15 will be opposed to that of winding 16-17,

I as regards the effect of these forces in producing a current in the test circuit. Consequently'if the twoplectromotive forces are equal in ma itude, as will be the case if themutual inductance between the wind- 10-11 and 14-15 is equal to the mutual inductance between the windings 10-11 and 16-17, no current will flow in the test circuit including the windings 14-15 and 16-17 and the telephone receiver. But, if,

of difiercnces in permeability be- 'tween the core sections 2 and 4- or of the lack ofsymmetry of the two coresections and the windings 14-15 and 16-17 with respect or from other causes, the mutual inductance between the winding 10-11 and the winding 14-15 is not the same as the mutual inductance between the winding 10-11 and the winding 16-17, the electromotive forces in the windings 14-15 and 16-17 will not balance and vibratory current will be set up in the circuit including the windings 14-15 and 16-17, and consequently the telephone receiver will be energized.

I The wire forming the continuation of one of the terminals as 11 of the main winding 10-11 is thereupon wrapped a number of times around one of the ad acent core sections, for instance 2, to form the supplementary winding 110-111, the number and direction of its turns and their position on the core section being adjusted by trial to reduce the tone in the telephone receiver to a minimum, that is, to introduce into the core section 2 additional flux of such strength and direction as to counterbalance, as nearly as possible, the difference between the inductance from winding 10-11 to winding 1415 and that from winding 10-11 to winding 16-17. Current of telephonic frequency is next applied to winding 12-13 in core section. 3, the windings 10-11 and 16-17 being connected in the test circuit as before. The wire forming the terminal 13, forinstance, of the main winding 12-13, is formed into a supplementary winding 112-113 on the'core section 4, this winding being adjusted, in the same manner as was supplementary winding 110-111, until the tone in the telephone receiver is again reduced to a minimum.

The above procedure establishes inthe loading unit substantial balance of the inductive effects of line conductor .101, rep resented by windings 10-11 and 110-111 upon windings 14-15 and 16-17 respectively, and independently.establishes a like condition with respect to the inductive effects of line counductor 102, represented by windings 12-13 and 112-113, upon windings 14-15 and 16-17 respectively. This results in reducing the inductive interference or cross-talk arising in the coil between the physical or side circuit I, and physical or side circuit II, and also between the derived phantom circuit III and the physical circuit II.

In the same way currents of telephonic fre- 'quency are applied to the windings 14-15 and 16-17 respectively, and supplementary windings 114-115 and 116-117 respectively are placed in series with these main windings and adjusted upon the core sections 3 and 1. This further reduces the cross-talk between thevside circuits I and II and also reduces the-cross-talk between the "phantom circuit HI'andthe side circuit I.

applied to a loading unit of the type above described, has reduced the cross-talk between the physical circuitsto about one-twelfth of its former magnitude and the cross-talk between the phantom circuit and the physical circuits to about one-sixth of its formermagnitude.

The modification shown in Figs. 1 and 5 involves the application of this invention to a simple toroidal coil comprising a. plurality of core sections 6, 7, 8 and 9. On each of the four core sections are placed an inner and an outer main winding section, the outer winding section on one core section and the inner winding section on the opposite core section forming a main'windingfor one of the hue conductors, the sectlons of the main winding for the other line conductor of the same physical circuit being arranged in the reverse order on this same pair of opposite core sections, as descrlbed 1n Campbell-Shaw Patent 980,921, issued January 10, 1911, and

Fondiller Patent 1,210,628 issued January 2, 1917.

In series with each of the four two-section main windings is a supplementary winding, which is placed upon one of the core sections between the core sections which carry the main winding sections. Thus the physical circuit 1 includes as'part of one line conductor the main winding section 20-21 on core section 6, main winding section 22-23 on core section 8 and supplementary winding" 120-128 on core section 7, and also includes in series therewith as part of the other line conductor, main winding section 28-29 on core section 6, main winding section 80-31- on core section 8 and supplementary winding 128-131 on core section 9, the main winding sections 2 1-25 and 26-27, supplementary winding 124-127, main winding sections 32-83'and B l-35, and supplementary winding 132-135 being similarly arranged in physical circuit II. The supplementary windings 120-123, 124-127, 128-131 and 132-135 are adjusted in the same way as described in connection with the supplemental-y windings shown in Fig. 1.

It is to be understood, of course, that it is not essential in all cases that there be a supplementary winding on each core section, since cases may occur where one or more of thesupplementary windings may be omitted. It is also within the scope of this invention to place both the supplementary windings that are included in: one physical circuit upon either one ofthe core.

sections whose main windings are in ,the other physical circuit, provided that the number and direction of turns are properly adjusted. Other modifications may also be made, as required by the circumstances under which thewinyentiondefined in the sub joined claims are to be used.

What is claimed is:

s5 1. The method of compensating for differences in permeability between sections oi the core of an nductance coll which carry the different main windings for the physical c1rcu1ts in which the coil is to be connected,

. windings of a loading coil adapted for use with two physical circuits and a derived phantom circuit and which comprisesa core on which the windings of one physical cir; cuit are arranged alternately with the windings of the other physical circuit, which consists in including in series "with each physical circuit winding a supplementary 'winding mounted on an adjacent section of the core and adjusting by trial the number and direction of turns of said auxiliary windings to balance inductively the wind- -ings of each physical circuit with respect to the windings of the other physical cir-' cuit both for side workingand for phantom working.

3. The method of compensating for differences of mutual inductance between the windings of a loading coil adapted for use with two physical circuits and a derived phantom circuit and which comprises a core on which the windings for one physical circuit are arranged alternately with the wind ings for the other physical circuit, which consists in including in series with one wind ing of one physical circuit a supplementary winding mounted on the same section of the core as one winding of the other physical circuit and adjusting by trial said supple mentary winding so as to produce equal mutual inductances between said first named winding and each of the two windings of adapted for simultaneously loading two physical circuits and a derived phantom circuit, which consists in connecting the windings for one physical circuit in series with a telephone receiver or the like in the same relation thatsaid windings are to be connected in said physical circuit, placing on the section of the coil including" one of said windings; a supplementary winding connected to one of the windings for the other physical circuit, passing a current of telephonic frequency through said last named winding and the supplementary winding, and adjusting the supplementary winding until the tone produced in the telephone receiver is a minimum, and repeating said prg-l cedure wlth each of the rem-ammg wlndlngs and the two windings for the physical circuit in which said winding is not to be connected{ In witness whereof, I hereunto subscribe my name this 5th day of August A. D., 1918.

WM. J. SHAGKELTON. 

